Paint Replacement Film, Composites Therefrom, and Related Methods

ABSTRACT

Paint replacement films of the invention comprise at least one adhesive layer; at least one pigmented layer; and at least one polymer layer that is essentially free of low surface energy materials. In addition, paint replacement composite articles and related methods of the invention comprise a paint replacement film and a topcoat on a surface of the paint replacement film opposite the adhesive layer. Paint replacement films and composite articles of the invention are useful when applied to a variety of articles (e.g., a motorized vehicle such as an aircraft).

BACKGROUND OF THE INVENTION

The present invention relates generally to films and composite articlesfor paint replacement and methods related to the same.

Painted surfaces are commonly used in many different types ofapplications. Painted surfaces can not only improve aesthetic propertiesof a surface, but they can also improve functional properties ofunderlying surfaces and help protect the same. One such application isin the transportation industry, where exterior painted surfaces aretypically exposed to a variety of environments, some of which can bevery harsh on the surface. Examples of articles in the transportationindustry having such painted surfaces include vehicles providingtransportation over land, in the water, and in the air. Such vehiclesinclude aircraft and motorized vehicles like automobiles and trucks. Thepaint on such surfaces can function to protect the underlying surfacefrom damage due to that exposure. However, the paint itself must also bedurable to withstand repeated exposure to such damaging environments.

Painting exterior surfaces on vehicles poses many challenges, not onlydue to the amount of surface area typically requiring painting and theoften uneven topography of such surfaces, but also due to increasinglystringent environmental regulations. For example, there is a desire forand increasingly regulations requiring a reduction in Volatile OrganicComponent (VOC) emissions, particularly in industries utilizingsignificant amounts of paint and other organic chemicals. VOC emissionreduction and water conservation, both associated with conventionalpainting processes, are therefore increasingly important environmentalconsiderations.

A further consideration associated with painting exterior surfaces onvehicles, particularly in the transportation industry, is overallweight. The presence of paint on a surface, while increasing theaesthetic and functional properties of the surface, also increases theweight of the article to which it is applied. In the transportationindustry, additional weight leads to consumption of excess fuel andrestrictions on the number of passengers or amount of cargo that anassociated vehicle can safely and efficiently transport.

Further, a unique consideration associated with painting or otherwisecovering exterior surfaces on aircraft and similar vehicles is theimpact of the relatively high vehicle speeds on the surface of thevehicle and any coatings or coverings thereon. For example, windresistance associated with travel at high speeds can make it difficultto retain uniform and adequate adherence of such coatings or coveringson a vehicle's surface. Thus, coatings and coverings developed forapplication to exterior surfaces of vehicles traveling on, for example,land are often not adequate to withstand the challenging conditionsassociated with higher speeds of travel through air.

To overcome many of the challenges associated with painting exteriorsurfaces of vehicles using conventional methodology, a number of paintreplacement technologies have been developed so that use of paint can beminimized or avoided. For example, by infusing plastic with pigment, onecommercially available product allows car manufacturers to remove thepainting process from automobile production lines. Such a product, whichcomprises a resin for formation of surfaces that are traditionallypainted, is marketed under the LEXAN SLX trade designation by GeneralElectric Company of Fairfield, Conn. It is advertised that one can nowachieve a high-gloss, sun- and scratch-resistant finish without the needfor paint when using such a resin.

Other alternatives to using conventional paint include adherence of apaint replacement film or sheet to a surface. For example, 3M Company ofSt. Paul, Minn. markets paint replacement films and tapes. It isadvertised that such films were created while developing top-coat paintreplacement technology for use on the demanding exterior surfaces ofaircraft. Further, it is advertised that such films couple the lowsurface energy performance of fluoropolymer films with a range of selfstick and curing adhesives. See also U.S. Patent Publication No.2007/0047099 and U.S. Pat. No. 7,141,303, both of which are assigned to3M Innovative Properties Company.

U.S. Pat. No. 5,965,256, also assigned to 3M Innovative PropertiesCompany, describes protective and decorative film-based coatings forsurfaces exposed to adverse environments, including outdoor weather,solvents, dirt, grease, marine environments, and the like. One filmexemplified therein is described as an aircraft paint replacement film.Such films include interpenetrating polymer networks, described aspreferably acrylate-urethane interpenetrating polymer networks (IPN).They may optionally have a layer of a highly fluorinated polymer at theoutermost, exposed surface. The substrate on which the films are adheredcan be a cured adhesive, preferably a cured pressure-sensitive adhesive(PSA), in which case the fluoro-containing polymer layer is said totypically be situated between the PSA layer and the IPN layer.Alternatively, the substrate can be a surface to be protected fromexposure to weather, chemical exposure, graffiti, or the like on, forexample, a vehicle such as an automobile, a truck, a boat, or anaircraft; an outdoor sign; or a building's exterior.

U.S. Pat. No. 6,475,616, also assigned to 3M Innovative PropertiesCompany, describes paint replacement appliqués comprising: a backingcomprising a fluorinated polymer having two treated surfaces, anadhesive layer on one treated surface and a cured urethane coating layeron the other treated surface. The cured urethane coating layers on theappliqués are made from the reaction products of a hydroxy-containingmaterial (base material) and isocyanate-containing material (activator).The curable compositions having the hydroxy- and isocyanate-containingmaterials may also further comprise a colorant. The curable compositionsusually contain solvents and may also further contain other additivessuch as UV-stabilizers, antioxidants, corrosion inhibitors, curingcatalysts, and the like. It is stated that, when dried and cured, theurethane coating layer provides a conformable urethane coating layerthat has improved gloss retention and gouge and scratch resistance ascompared to, for example, a fluoropolymer layer alone.

However, these 3M films have not proven reliable in maintaining theirintegrity and adherence to the underlying surface when exposed to theenvironment under expected operating conditions. A contributor to thisundesirable quality is the nature of bonding between the film andunderlying surface (i.e., bonds relying on Van Der Waals forces, such asthose typically associated with use of pressure sensitive adhesives, asopposed to stronger bonds, such as covalent bonds). Further, it isbelieved that inclusion of fluoropolymer layers in such filmscontributes to interlayer delamination due to its low surface energy andinadequate bonding to adjacent layers. Still further, if additionalcoatings or coverings are desired to be applied to the exterior surfaceof such films, the low surface energy fluoropolymer films therein makeit challenging to find a coating or covering that will adequately adherethereto.

3M Company also markets films for application over painted surfaces thatare intended to help maintain the beauty and integrity of such surfaces.These films are marketed under the SCOTCHGARD PAINT PROTECTION FILMtrade designation. The urethane films are described as being useful onvulnerable exterior painted surfaces such as leading hood edges, fenderend caps and rocker panels to protect against stone chips, bug damage,abrasion and weathering. The film is advertised as being transparent andnearly invisible, such that it does not alter a vehicle's appearance.

U.S. Pat. No. 7,141,294, assigned to 3M Innovative Properties Co.describes a decorative film using no appreciable amount, or no amount,of polyvinyl chloride. This decorative film comprises a substrate, anadhesive layer for sticking the decorative film to an adherend formed onone surface of the substrate, a printed layer provided with a printeddecorative pattern or character information formed on the other surfaceof the substrate, and a top clear layer for protecting the printedlayer. The substrate is formed from an ethylene-(meth)acrylic acidcopolymer. The top clear layer used as an outer-most layer is preferablymade of a material which is superior in weatherability and waterresistance and has high transparency (e.g., colorless coatingcompositions such as fluororesins, thermosetting urethanes, andultraviolet-curing compositions). The decorative film is described ashaving flexibility for adhering, ink adhesion, water resistance, andweatherability with good balance. It is also described as being suitablefor various adherends, particularly for adhering to buildings orvehicles used outdoors, including curved surfaces such as the body ofvehicles.

U.S. Pat. No. 5,034,275 refers to a paint-coated sheet material. Thematerial purportedly comprises a flexible and stretchable thermoplasticpolyester carrier film, a stretchable aqueous polyurethane paint layer,a stretchable transparent crosslinked polyurethane topcoat layer and,disposed between the carrier film and the paint layer, a thin tie layerformed by coating an aqueous dispersion of a neutralized copolymer ofethylene and an ethylenically unsaturated carboxylic acid on the carrierfilm. The thickness of the crosslinked polyurethane topcoat layer isstated to be substantially thicker than the paint layer, which is statedto have a thickness of 12 to 80 microns. In that regard, the topcoatlayer has a thickness in the range of about 0.02 to 0.25 millimeter (20microns to 250 microns), preferably from about 0.03 (30 microns) to 0.1millimeter (100 microns).

U.S. Pat. No. 5,114,789 describes a decorative sheet material having atransparent topcoat that can be bonded to various substrates, such asexterior automotive panels, as a protective and decorative coating. Thesheet material comprises a thin carrier film, a paint layer adhered toone surface of the carrier film, and a crosslinked topcoat layer. Thattopcoat layer is stated to be “extremely thick”—at least 0.1 millimeter(100 microns)—in embodiments described therein.

U.S. Pat. No. 5,242,751 describes a paint composite article including athermally deformable carrier film having, on its first major surface, anadhesive layer and, on its second major surface, a paint layerconsisting of a pigmented basecoat covered by a polyurethane topcoatlayer.

U.S. Pat. No. 5,268,215 describes a paint-coated film purportedly havinggood mar resistance. A polyurethane paint layer is coated on a polymericcarrier film. Coated on the upper surface of the paint layer is apolyurethane clearcoat layer, which is then coated with apolyurethane-siloxane topcoat layer. The film can purportedly bethermoformed, stretched, and bonded adhesively to auto body parts,boats, household appliances, and other substrates as protective anddecorative coverings having a basecoat-clearcoat appearance.

U.S. Pat. No. 5,468,532 describes a multi-layer graphic article with acolor layer. It is based on a polymeric film that is covered with aprotective surface layer to purportedly make the article weatherable andresistant to chemical exposure. The protective surface layer isdescribed as being a polyurethane-based material in an exemplaryembodiment.

U.S. Pat. No. 6,132,864 describes a painted plastic film, which iscoated with two or more coats of certain materials. It consists of abase plastic film, which is first coated with a filler composition,followed by coating with a pigmented paint, and then coating with atransparent plastic film. The base plastic film can be a polyolefin, apolyamide, a polyurethane, a polyester, a polyacrylate, a polycarbonateor mixture of different polymeric substances. The filler composition isdescribed as a composition containing a binder and crosslinking agentamong other components. The pigmented paint coating is described as atopcoat comprising a polymeric binder, with or without a crosslinkingagent, and a pigment or mixture of pigments. The transparent plasticfilm is described as being one of the same materials suitable for use asthe base film. The multi-layer sheets described therein purportedly havegood resistance to stone chipping and corrosion.

Despite the number of paint replacement technologies, conventionaltechnology has not satisfactorily addressed paint replacement in allsituations, particularly applications involving vehicles used for airtransportation. Not only are adequate adhesion and durability issues forexterior surfaces on such vehicles due to their typical exposure to highwind resistance, but other issues exist as well. For example, manyaircraft and other transportation vehicles increasingly rely on use ofcomposite materials for surfaces to which conventional paint replacementmaterials are adhered. Conventional paint replacement materials,however, often do not adhere as well to composite materials as they doto individual materials.

It is known that the ability of conventional paint replacement materialsto adhere adequately to all surfaces, including those formed fromcomposite materials, and provide the desired aesthetic and functionalproperties is often inadequate. Not only is it desirable for a materialto adhere adequately to a surface, but it is also desirable to be ableto remove the material easily when desired. In the case of an aircraft,for example, company logos and designs often change, which leads to adesire to refinish aircraft displaying outdated logos and designs. Thisis particularly prevalent in the case of leased aircraft, which oftenundergo multiple and repeated changes of possession and, thus, changesin associated individual or company logos and designs. Typically paintreplacement films present on a surface must first be removed whenrefinishing the surface. Many conventional films, however, are noteasily removable as the layers therein are prone to delamination.Delamination of the paint replacement film when removing the same from asurface can significantly complicate the refinishing process.

Even when paint, as opposed to a paint replacement film, is present on asurface to be refinished, the refinishing process can be problematic.Refinishing painted surfaces typically entails sanding the surface inpreparation for applying a fresh coat of paint thereon. Compositematerial surfaces must usually rely on sanding to remove undesired paintthereon when refinishing because most chemical strippers are not able tobe used on composite materials. Sanding surfaces formed from compositematerials, however, is also not desirable due to the likelihood thatsuch sanding will result in damage to (e.g., breakage of) thecomposite's reinforcement material (especially when that reinforcementmaterial comprises fibers).

As noted, a number of problems are inadequately addressed byconventional paint replacement technologies. Thus, alternative paintreplacement technologies are desired.

BRIEF SUMMARY OF THE INVENTION

Paint replacement films of the invention comprise at least one adhesivelayer; at least one pigmented layer; and at least one polymer layer thatis essentially free of low surface energy materials. According to anexemplary embodiment, the paint replacement film excluding the at leastone adhesive layer has a thickness of about 25 microns to about 50microns. It has been found that use of a relatively thin paintreplacement film contributes to superior flexibility, allowing paintreplacement films of the invention to be effectively used in coveringarticles (e.g., aircraft) having curved or other non-planar surfaces.

In order to reduce the possibility of interlayer delamination uponremoval of the film from a surface as desired, adjacent layers withinthe paint replacement film are covalently bonded to each other inaccordance with one embodiment of the invention. For example, surfacetension of each layer within the paint replacement film can be withinabout 5 dynes per centimeter of surface tension of adjacent layerstherein.

The pigmented layer may be continuous or discontinuous. In oneembodiment, the pigmented layer comprises ink. Preferably, the pigmentedlayer has a maximum thickness of about 25 microns. According to anexemplary embodiment, the pigmented layer has a thickness of about 5microns to about 8 microns.

In an exemplary embodiment, the polymer layer is polyurethane-based.Preferably the polymer layer has a thickness of about 10 microns toabout 50 microns. According to an exemplary embodiment, the polymerlayer has a thickness of about 25 microns or less.

In one embodiment, the adhesive layer comprises a pressure-sensitiveadhesive (e.g., a (meth)acrylate). Preferably, the adhesive layer has athickness of about 5 microns to about 150 microns. According to anexemplary embodiment, the adhesive layer has a thickness of about 30microns to about 100 microns. In a further embodiment, the adhesivelayer has a thickness of about 25 microns or less.

Paint replacement films of the invention are useful when applied to avariety of articles (e.g., a motorized vehicle such as an aircraft). Inone embodiment, such an article comprises at least one surface having onat least a portion thereof a paint replacement film of the invention.

In addition, paint replacement composite articles of the inventioncomprise a paint replacement film and a topcoat on a surface of thepaint replacement film opposite the adhesive layer. In an exemplaryembodiment, the topcoat comprises a polyurethane-based material. Inanother exemplary embodiment, the topcoat comprises a clearcoat. Whilethe topcoat within paint replacement composite articles can comprise anysuitable thickness, preferably the topcoat is about 20 microns to about40 microns thick.

Methods of the invention include a method of protecting a surface, themethod comprising: adhering a paint replacement film to at least aportion of at least one exterior surface of an article, and applying atopcoat to essentially the entire exposed exterior surface of thearticle, except for those surfaces where the topcoat would detract fromfunction of the underlying surface or article. In an exemplaryembodiment, the article comprises an aircraft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The phrase “paint replacement film” encompasses films includingessentially one uniform color throughout as well as films which, bythemselves or in combination with other paint replacement films, includegraphics, patterns, and other non-uniformly dispersed color variationsthroughout. Paint replacement films of the invention generally include apolymer layer and an adhesive layer with a pigmented layer disposedtherebetween and/or a pigmented layer disposed on the exterior surfaceof the polymer layer. The pigmented layer provides the uniform ornon-uniform color throughout the film.

In a preferred embodiment, the polymer layer, the pigmented layer, andthe adhesive layer are selected to be chemically compatible with eachother to improve interlayer adhesion of the paint replacement film. Forexample, material properties contributing to high chemical affinity ofthe various layers with each other are identified and selected accordingto this embodiment of the invention. According to one aspect of thisembodiment, the surface tension of each layer within the paintreplacement film is within about 5 dynes per centimeter of the surfacetension of adjacent layers therein. According to another aspect of thisembodiment, the chemistries of adjacent layers within the paintreplacement film are selected such that covalent bonds form between thelayers. Although primers may be used between adjacent layers, they arenot required in paint replacement films according to the invention. Eachof the layers is described in further detail below.

Adhesive Layer

While more than one adhesive layer can be used in paint replacementfilms of the invention or the adhesive layer can comprise more than onedistinct adhesive, the following description is made with reference toone such layer and type of adhesive within that layer for simplicityonly. Recognize that, if multiple adhesives or adhesive layers are used,each adhesive or adhesive layer can be the same or different.

The adhesive layer comprises any suitable material. According to oneembodiment, the adhesive layer generally comprises a base polymer withone or more additives. While any suitable chemistry can be used for thebase polymer in the adhesive layer, (meth)acrylate (i.e., acrylate andmethacrylate) chemistry is preferred. In particular, an adhesive basedon 2-ethyl hexyl acrylate, vinyl acetate, and acrylic acid monomerspolymerized as known to those skilled in the art can be used as the basepolymer. However, other suitable chemistries are known to those skilledin the art and include, for example, those based on synthetic andnatural rubbers, polybutadiene and copolymers thereof, polyisoprene andcopolymers thereof, and silicones (e.g., polydimethylsiloxane andpolymethylphenylsiloxane). In a preferred embodiment, the adhesive layercomprises a pressure-sensitive adhesive (PSA).

Any suitable additives can optionally be used in conjunction with thebase polymer in the adhesive layer. For example, stabilizers (e.g.,antioxidants, heat stabilizers, and UV-stabilizers), crosslinkers (e.g.,aluminum or melamine crosslinkers), corrosion inhibitors, tackifiers,plasticizers, photocrosslinkers, colorants, fillers, and otherconventional adhesive additives as known to those of ordinary skill inthe art can be incorporated into the adhesive layer. If desired, anadhesion promoter may be included in the adhesive layer. However, inpreferred embodiments, the material comprising the adhesive layer isselected to be chemically compatible with adjacent layers of the paintreplacement film. Thus, an adhesion promoter is not required accordingto preferred embodiments of the invention.

Preferably, the adhesive layer is essentially free of components thatmay tend to migrate to the outer surface of the paint replacement filmor to an interface therein, where such components may promote interlayerdelamination or otherwise detrimentally affect the adherence of thepaint replacement film to adjacent surfaces or layers. The adhesivelayer is also preferably resistant to chemicals to which it may beexposed during use of the paint replacement film. For example, it ispreferred that the adhesive layer is resistant to degradation by waterand hydraulic fluids (e.g., those sold by TBM, Inc. of St. Louis, Mo.under Solutia, Inc.'s SKYDROL trade designation).

The adhesive layer comprises any suitable thickness. In one embodiment,the adhesive layer has a thickness of about 5 microns to about 150microns. In a further embodiment, the adhesive layer has a thickness ofabout 30 microns to about 100 microns. In an exemplary embodiment, theadhesive layer is about 25 microns thick or less. However, the thicknessof the adhesive layer can vary substantially without departing from thespirit and scope of the invention.

Pigmented Layer

While more than one pigmented layer can be used in paint replacementfilms of the invention, the following description is made with referenceto one such layer for simplicity only. Recognize that, if multiplepigmented layers are used, each pigmented layer can be the same ordifferent.

The pigmented layer comprises any suitable material and provides desiredaesthetics when the paint replacement film is adhered to a surface. Thepigmented layer can be a continuous or discontinuous layer. Note thatthe pigmented layer may consist essentially of graphics, patterns, andthe like, which results in the layer being a discontinuous layer and/ora non-planar layer.

In an exemplary embodiment, the pigmented layer comprises ink. Anysuitable commercially available ink can be used. Non-limiting examplesof suitable inks include pigmented acrylic ink (including pigmentedfast-dry acrylic ink), pigmented urethane ink, epoxy ink, and a urethaneenamel coating such as that sold by PRC Desoto International, Inc. ofGlendale, Calif. under the trade designation, DESOTHANE HS.

The pigmented layer generally comprises at least one material impartingdesired color to the layer or portion thereof. Any suitable additivescan optionally be used in the pigmented layer. For example, stabilizers(e.g., antioxidants, heat stabilizers, and UV-stabilizers), crosslinkers(e.g., aluminum or melamine crosslinkers), corrosion inhibitors,plasticizers, photocrosslinkers, additional colorants, fillers, andother conventional additives as known to those of ordinary skill in theart can be incorporated into the pigmented layer. If desired, anadhesion promoter may be included in the pigmented layer. However, inpreferred embodiments, the material comprising the pigmented layer isselected to be chemically compatible with adjacent layers of the paintreplacement film. Thus, an adhesion promoter is not required accordingto preferred embodiments of the invention.

Preferably, the pigmented layer is essentially free of components thatmay tend to migrate to the outer surface of the paint replacement filmor to an interface therein, where such components may promote interlayerdelamination or otherwise detrimentally affect the adherence of thepaint replacement film to adjacent surfaces or layers. The pigmentedlayer is also preferably resistant to chemicals to which it may beexposed during use of the paint replacement film. For example, it ispreferred that the pigmented layer is resistant to degradation by waterand hydraulic fluids (e.g., those sold by TBM, Inc. of St. Louis, Mo.under Solutia, Inc.'s SKYDROL trade designation), particularly when thepigmented layer comprises an outer layer of the paint replacement film.

The pigmented layer comprises any suitable thickness. In an exemplaryembodiment, the pigmented layer has a maximum thickness of about 25microns, preferably about 5 microns to about 8 microns.

Polymer Layer

While more than one polymer layer can be used in paint replacement filmsof the invention or the polymer layer can comprise more than onedistinct polymer, the following description is made with reference toone such layer and type of polymer within that layer for simplicityonly. Recognize that, if multiple polymers or polymer layers are used,each polymer or polymer layer can be the same or different.

The polymer layer comprises any suitable material. For example, thepolymer layer may comprise a urethane film, an acrylic film, an epoxyfilm, or a polyester film (e.g., that available from DuPont under theMYLAR trade designation). Although generally not preferred due to itslack of flexibility, the polymer layer can also be a vinyl, such aspolyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), or generalpolyvinyl fluoride (PVF) (e.g., that available from DuPont under theTEDLAR trade designation). Nevertheless, generally the polymer layer isessentially free of low surface energy materials (e.g., silicones andfluoropolymers), which tend to promote interlayer delamination.

The polymer layer is preferably polyurethane-based in that it comprisesany suitable polyurethane material. For simplicity, the term“polyurethane” is sometimes used herein to reference polymers containingurethane (also known as carbamate) linkages, urea linkages, orcombinations thereof (i.e., in the case of poly(urethane-urea)s). Thus,polyurethanes of the invention contain at least urethane linkages and,optionally, urea linkages. Many commercially available polyurethanes areavailable and suitable for use as polyurethane-based polymer layersaccording to the invention. For example, polyurethanes are availablefrom Thermedics (Noveon, Inc.) of Wilmington, Mass. under the TECOFLEXtrade designation (e.g., CLA-93AV) and from Bayer MaterialScience LLC ofPittsburgh, PA under the TEXIN trade designation (e.g., an aliphatic,ester-based polyurethane available under the trade designation, TEXINDP7-3008).

Any suitable additives can optionally be included in the polymer layer.For example, stabilizers (e.g., antioxidants, heat stabilizers, andUV-stabilizers), crosslinkers (e.g., aluminum or melamine crosslinkers),binders, corrosion inhibitors, plasticizers, photocrosslinkers,colorants, fillers, and other conventional additives as known to thoseof ordinary skill in the art can be incorporated into the polymer layer.If desired, an adhesion promoter may be included in the polymer layer.However, in preferred embodiments, the material comprising the polymerlayer is selected to be chemically compatible with adjacent layers ofthe paint replacement film. Thus, an adhesion promoter is not requiredaccording to preferred embodiments of the invention.

The polymer layer may be clear or pigmented depending on theapplication. When the polymer layer is clear, the pigmented layer istypically provided between the polymer layer and the adhesive layer.Alternatively or in conjunction with another pigmented layer, when thepolymer layer is clear, a pigmented layer can be provided on the outersurface of the polymer layer. When the polymer layer is pigmented, thepigmented layer is generally provided on the outer surface of thepolymer layer. In this embodiment, the polymer layer can be impregnatedwith a material (e.g., titanium dioxide) that causes the polymer layerto function as a reflective background, bringing out the color of theoverlying pigmented layer.

Preferably, the polymer layer is essentially free of components that maytend to migrate to the outer surface of the paint replacement film or toan interface therein, where such components may promote interlayerdelamination or otherwise detrimentally affect the adherence of thepaint replacement film to adjacent surfaces or layers. The polymer layeris also preferably resistant to chemicals to which it may be exposedduring use of the paint replacement film. For example, it is preferredthat the polymer layer is resistant to degradation by water andhydraulic fluids (e.g., those sold by TBM, Inc. of St. Louis, Mo. underSolutia, Inc.'s SKYDROL trade designation). It is also preferred thatthe polymer layer is thermally resistant to temperatures to which it maybe exposed during use of the paint replacement film. For example,exterior surfaces or coverings of an aircraft are often exposed totemperatures ranging from about −55° C. to about +75° C. Thus, it ispreferred that the polymer layer is resistant to degradation whenexposed to such temperature variations.

The polymer layer comprises any suitable thickness. In one embodiment,the polymer layer has a thickness of about 10 microns to about 50microns. In an exemplary embodiment, the polymer layer is about 25microns thick or less. It has been found that use of a relatively thinpolymer layer contributes to superior flexibility of the paintreplacement film. Such flexibility allows paint replacement films of theinvention to be effectively used in covering articles (e.g., aircraft)having curved or other non-planar surfaces.

Optional Topcoat

According to a preferred embodiment of the invention, a topcoat isapplied to the exterior surface of the paint replacement film on a sideopposite the adhesive. In this embodiment, the topcoat overlays thepaint replacement film to form a paint replacement composite article.

In one embodiment, a topcoat is applied (e.g., by spraying or paintingit) on the paint replacement film after adherence of the paintreplacement film to an underlying surface. Preferably, the topcoat isapplied such that no paint replacement film is exposed to theenvironment when the composite article is adhered to a surface for use.Still further, when more than one paint replacement film is used incombination with others on a surface, the topcoat preferably covers andprotects seams between adjacent paint replacement films from exposure tothe environment.

The topcoat can comprise any suitable chemistry. In general, the topcoatprovides one or more properties including the following: environmentalresistance, chemical resistance, abrasion resistance, scratchresistance, optical transparency, and other often desirable properties.According to an exemplary embodiment, the topcoat comprises a materialwith the following properties: non-yellowing, gloss retention (e.g.,maintaining of gloss on the order of about 80 to about 90 gloss units),and extensibility.

In an exemplary embodiment, the topcoat comprises a polyurethane-basedmaterial. Many suitable topcoats are commercially available, includingfor example, polyurethane coatings sold by PRC Desoto International,Inc. of Glendale, Calif. under the DESOTHANE HS trade designation (e.g.,DESOTHANE HS BAC 900 (CA8000/B900A or CA8000/B900B)) or those sold byAkzo-Nobel Aerospace Coatings of Waukegan, Ill. under the ECLIPSE tradedesignation (e.g., ECLIPSE BAC 900).

Preferably, chemistry of the topcoat is selected to facilitate itsbonding to the underlying paint replacement film. According to oneaspect of this embodiment, the surface tension of the outer layer of thepaint replacement film is within about 5 dynes per centimeter of thesurface tension of the overlying topcoat. According to another aspect ofthis embodiment, the topcoat comprises excess isocyanate-functionalmoieties reactive with excess isocyanate-reactive moieties in theexterior layer of the paint replacement film on which it is applied.According to this aspect of the invention, covalent bonds form betweenthe topcoat and paint replacement film. Such covalent bonds aretypically more robust than other types of bonds (e.g., those relying onVan Der Waals forces, such as those typically associated with use ofpressure sensitive adhesives) and are, therefore, preferred.

Any suitable additives can optionally be included in the topcoat. Forexample, stabilizers (e.g., antioxidants, heat stabilizers, andUV-stabilizers), crosslinkers (e.g., aluminum or melamine crosslinkers),binders, corrosion inhibitors, plasticizers, photocrosslinkers,colorants, fillers, and other conventional additives as known to thoseof ordinary skill in the art can be incorporated into the topcoat. Thetopcoat layer may be clear or pigmented depending on the application.When clear, which is preferred so that the pigmented layer is outwardlyvisible, the topcoat is referred to as a “clearcoat.”

As applied, the topcoat is preferably resistant to chemicals to which itmay be exposed during use of the paint replacement composite article.For example, it is preferred that the topcoat is resistant todegradation by water and hydraulic fluids (e.g., those sold by TBM, Inc.of St. Louis, Mo. under Solutia, Inc.'s SKYDROL trade designation). Itis also preferred that the topcoat is thermally resistant totemperatures to which it may be exposed during use of the paintreplacement composite article. For example, exterior surfaces orcoverings on an aircraft are often exposed to temperatures ranging fromabout −55° C. to about +75° C. Thus, it is preferred that the topcoat isresistant to degradation when exposed to such temperature variations.

The topcoat is applied on the exterior surface of the paint replacementfilm to a desired thickness according to coating methodology known tothose skilled in the art. In an exemplary embodiment, the total drythickness of the applied topcoat is about 10 microns to about 60microns, preferably about 20 microns to about 40 microns. Depending onthe desired thickness, the topcoat can be applied in one or more coatinglayers. For example, two individual coating layers comprise the topcoataccording to one embodiment. In this embodiment, each coating layer issprayed wet, but not so wet as to flow unevenly across the surface andcreate a significantly non-uniform topcoat.

While this embodiment employing a topcoat is described with reference tothe improved paint replacement films of the invention, recognize thatthis aspect of the invention is applicable to use with any conventionalpaint replacement film or similar underlying material.

Applications

Until the paint replacement film is adhered to a surface, it can bestored with an optional release liner adjacent the adhesive layer andwith an optional carrier on the opposite side thereof. The selection anduse of such carriers and liners is within the knowledge of one ofordinary skill in the art.

When applied, paint replacement films can cover substantially all of orselect portions of exterior surfaces on a variety of articles, such astransportation vehicles. The paint replacement film can be applied to asurface according to principles and methodologies understood by those ofordinary skill in the art. For example, the release liner, if present,is first removed. Then, the surface to which the paint replacement filmis to be adhered can optionally be sprayed with a cleaning and/oranti-slip agent (e.g., a mixture of 3 parts water to 1 partisopropanol). The adhesive layer of the paint replacement film may alsobe sprayed with such an agent. Still further, once the paint replacementfilm is positioned over the surface to which it is to be applied, thefilm may also be sprayed with such an agent. Thereafter, the paintreplacement film is firmly adhered to the underlying surface using, forexample, a squeegee. Excess cleaning and/or anti-slip agent is thenremoved from the surface and the film is allowed to set for a timesufficient to prevent inadvertent removal of the film upon removal ofany carrier used in conjunction therewith. The carrier, if present, isthen removed.

After they are adhered to a surface as known to those of ordinary skillin the art, an exemplary method of which is described above, theoptional topcoat is applied in one embodiment. If desired, the outerlayer of the paint replacement film is primed with a cleaning agent(e.g., a mixture of 3 parts water to 1 part isopropanol) to remove anycontamination before the optional topcoat is applied.

Recognize that, when used, the topcoat may be applied over a discreteportion of the paint replacement film adhered to a surface. It ispreferred, however, that the topcoat is applied to encapsulateessentially all of the paint replacement film. When applied to anaircraft, for example, it is particularly preferred to apply the topcoatto essentially the entire exposed surface of the aircraft, except forthose surfaces where the topcoat would detract from the function of theunderlying surface (e.g., as in the case of windows, which may be tapedor otherwise covered during application of the topcoat to preventcoating thereof).

Paint replacement films of the invention are useful for application to awide variety of exterior surfaces. For example, such paint replacementfilms find particularly beneficial use when adhered to exterior surfacesof many transportation vehicles. In an exemplary embodiment, paintreplacement films of the invention are effectively and durably adheredto the exterior surface of an airborne transportation vehicle, whichvehicles are typically subject to extreme wind resistance and otherchallenging environmental conditions when in use. For example, the paintreplacement films are capable of being effectively and durably adheredto the exterior surface of an aircraft. The paint replacement films arealso capable of being efficiently removed from the surface of anaircraft when repair is needed due to the increased interlayer adhesion,which promotes removability of the paint replacement film in a unitarypiece when desired.

Not only do paint replacement films of the invention exhibit improvedresistance to interlayer delamination or inadequate adhesion during use,but they also have improved flexibility as compared to conventionalpaint replacement films. This flexibility, which is created in part dueto the overall thin dimensions of the paint replacement film (e.g.,about 25 microns to about 50 microns thick, not including the adhesivelayer), facilitates adequate and durable adherence of the film to curvedor otherwise non-planar surfaces.

Use of such paint replacement films and related articles facilitatesobtainment of many benefits as compared to use of traditional paint.These benefits include, for example, a reduction in VOC emissionsgenerated during manufacture of the article to which such compositearticles are applied, improved water conservation during suchmanufacture, decreased weight of the manufactured articles, moreconsistent surface quality (e.g., including consistent weightdistribution throughout the surface onto which the paint replacementfilm is applied) in such manufactured articles, and other benefits.

EXAMPLES

Exemplary embodiments and applications of the invention are described inthe following non-limiting examples and related testing methods.

Example 1

A paint replacement film was prepared with the following order ofconstruction and dimensions: a 20-micron thick, clear polyurethane film,a pigmented layer comprising images and characters, a 30-micron thickacrylic adhesive, and a 160 grams per square meter (gsm) poly-coatedkraft paper release liner. The paint replacement film was prepared foruse on an aircraft. Once applied to the exterior surface of an aircraft,a clearcoat can be applied as described herein. For example, a topcoat(e.g., clearcoat) having a thickness of about 20 to about 40 microns canbe wet-applied over the paint replacement film.

Example 2

A paint replacement film was prepared with the following order ofconstruction and dimensions: a 10-micron thick, clear polyurethane film,a pigmented layer comprising images and characters, a 15-micron thickacrylic adhesive, and a 160 grams per square meter (gsm) poly-coatedkraft paper release liner. The paint replacement film was prepared foruse on an aircraft. This film is preferred for application to portionsof an aircraft with highly curved surfaces (e.g., engine nacelle). Onceapplied to the exterior surface of an aircraft, a clearcoat can beapplied as described herein. For example, a topcoat (e.g., clearcoat)having a thickness of about 20 to about 40 microns can be wet-appliedover the paint replacement film.

Various modifications and alterations of the invention will becomeapparent to those skilled in the art without departing from the spiritand scope of the invention, which is defined by the accompanying claims.It should be noted that steps recited in any method claims below do notnecessarily need to be performed in the order that they are recited.Those of ordinary skill in the art will recognize variations inperforming the steps from the order in which they are recited.

1. An article comprising at least three distinct layers as follows: atleast one adhesive layer; a pigmented layer; and a polymer layer,wherein the article excluding the at least one adhesive layer has athickness of about 25 microns to about 50 microns and is essentiallyfree of fluoropolymer materials, and wherein each of the at least oneadhesive layer, the pigmented layer, and the polymer layer is covalentlybonded to at least one other layer within the article to form a paintreplacement film therefrom. 2-3. (canceled)
 4. The paint replacementfilm of claim 1, wherein surface tension of each layer within the paintreplacement film is within about 5 dynes per centimeter of surfacetension of adjacent layers therein.
 5. The paint replacement film ofclaim 1, wherein the pigmented layer comprises ink.
 6. The paintreplacement film of claim 1, wherein the pigmented layer isdiscontinuous.
 7. The paint replacement film of claim 1, wherein thepigmented layer has a maximum thickness of about 25 microns.
 8. Thepaint replacement film of claim 1, wherein the pigmented layer has athickness of about 5 microns to about 8 microns.
 9. The paintreplacement film of claim 1, wherein the polymer layer ispolyurethane-based.
 10. The paint replacement film of claim 1, whereinthe polymer layer has a thickness of about 10 microns to about 50microns.
 11. The paint replacement film of claim 1, wherein the polymerlayer has a thickness of about 25 microns or less.
 12. The paintreplacement film of claim 1, wherein the at least one adhesive layercomprises a pressure-sensitive adhesive.
 13. The paint replacement filmof claim 1, wherein the at least one adhesive layer comprises a(meth)acrylate.
 14. The paint replacement film of claim 1, wherein theat least one adhesive layer has a thickness of about 5 microns to about150 microns.
 15. The paint replacement film of claim 1, wherein the atleast one adhesive layer has a thickness of about 30 microns to about100 microns.
 16. The paint replacement film of claim 1, wherein the atleast one adhesive layer has a thickness of about 25 microns or less.17. An article comprising at least one surface having on at least aportion thereof the paint replacement film of claim
 1. 18. The articleof claim 17, wherein the article comprises a motorized vehicle.
 19. Thearticle of claim 17, wherein the article comprises an aircraft.
 20. Apaint replacement composite article comprising: the paint replacementfilm of claim 1, and a topcoat on a surface of the paint replacementfilm opposite the at least one adhesive layer.
 21. The paint replacementcomposite article of claim 20, wherein the topcoat comprises apolyurethane-based material.
 22. The paint replacement composite articleof claim 20, wherein the topcoat comprises a clearcoat.
 23. The paintreplacement composite article of claim 20, wherein the topcoat is about20 microns to about 40 microns thick.
 24. A method of protecting asurface, the method comprising: adhering the paint replacement film ofclaim 1 to at least a portion of at least one exterior surface of anarticle, and applying a topcoat to essentially the entire exposedexterior surface of the article, except for those surfaces where thetopcoat would detract from function of the underlying surface orarticle.
 25. The method of claim 24, wherein the article comprises anaircraft.
 26. An article comprising at least three distinct layers asfollows: an adhesive layer; a pigmented layer; and a polymer layer thatis essentially free of low surface energy materials, wherein all layerswithin the article are continuous to form a paint replacement filmcapable of flexibly adhering to a curved or otherwise non-planarsubstrate and capable of being removed in a unitary piece afteradherence of the paint replacement film to the substrate.
 27. A paintreplacement film consisting of sequential layers as follows: optionally,a release liner; at least one adhesive layer; at least one pigmentedlayer having a maximum thickness of about 8 microns; at least onepolymer layer that is essentially free of low surface energy materialsand comprises a urethane, an epoxy, an acrylic, or a polyester; andoptionally, a carrier opposite the release liner, wherein the paintreplacement film excluding the at least one adhesive layer has athickness of about 25 microns to about 50 microns, and wherein the paintreplacement film exhibits flexibility for adherence of the paintreplacement film to curved or otherwise non-planar surfaces, and whereinthe paint replacement film is capable of being removed in a unitarypiece after adherence of the paint replacement film to a substrate.